Book Image

Unity 2018 Artificial Intelligence Cookbook - Second Edition

By : Jorge Palacios
Book Image

Unity 2018 Artificial Intelligence Cookbook - Second Edition

By: Jorge Palacios

Overview of this book

Interactive and engaging games come with intelligent enemies, and this intellectual behavior is combined with a variety of techniques collectively referred to as Artificial Intelligence. Exploring Unity's API, or its built-in features, allows limitless possibilities when it comes to creating your game's worlds and characters. This cookbook covers both essential and niche techniques to help you take your AI programming to the next level. To start with, you’ll quickly run through the essential building blocks of working with an agent, programming movement, and navigation in a game environment, followed by improving your agent's decision-making and coordination mechanisms – all through hands-on examples using easily customizable techniques. You’ll then discover how to emulate the vision and hearing capabilities of your agent for natural and humanlike AI behavior, and later improve the agents with the help of graphs. This book also covers the new navigational mesh with improved AI and pathfinding tools introduced in the Unity 2018 update. You’ll empower your AI with decision-making functions by programming simple board games, such as tic-tac-toe and checkers, and orchestrate agent coordination to get your AIs working together as one. By the end of this book, you’ll have gained expertise in AI programming and developed creative and interactive games.
Table of Contents (12 chapters)

Wandering around

This technique works like a charm for random crowd simulations, animals, and almost any kind of NPC that requires random movement when idle.

Getting ready

We need to add another function to our AgentBehaviour class called OriToVec, which converts an orientation value to a vector:

public Vector3 GetOriAsVec (float orientation) { 
    Vector3 vector  = Vector3.zero; 
    vector.x = Mathf.Sin(orientation * Mathf.Deg2Rad) * 1.0f; 
    vector.z = Mathf.Cos(orientation * Mathf.Deg2Rad) * 1.0f; 
    return vector.normalized; 
} 

How to do it...

We can regard it as a big three-step process in which we first manipulate the internal target position in a parameterized random way, face that position, and move accordingly:

  1. Create the Wander class deriving from Face:
using UnityEngine; 
using System.Collections; 
 
public class Wander : Face 
{ 
    public float offset; 
    public float radius; 
    public float rate; 
} 
  1. Define the Awake function in order to set up the internal target:
public override void Awake() 
{ 
    target = new GameObject(); 
    target.transform.position = transform.position; 
    base.Awake(); 
} 
  1. Define the GetSteering function:
public override Steering GetSteering() 
{ 
    Steering steering = new Steering(); 
    float wanderOrientation = Random.Range(-1.0f, 1.0f) * rate; 
    float targetOrientation = wanderOrientation + agent.orientation; 
    Vector3 orientationVec = OriToVec(agent.orientation); 
    Vector3 targetPosition = (offset * orientationVec) + transform.position; 
    targetPosition = targetPosition + (OriToVec(targetOrientation) * radius); 
    targetAux.transform.position = targetPosition; 
    steering = base.GetSteering(); 
    steering.linear = targetAux.transform.position - transform.position; 
    steering.linear.Normalize(); 
    steering.linear *= agent.maxAccel; 
    return steering; 
} 

How it works...

The behavior takes two radii in order into consideration to get a random position to go next, looks toward that random point, and converts the computed orientation into a direction vector in order to advance:

A visual description of the parameters for creating the Wander behavior